Splenic memory CD8 T cell signature of enhanced responsiveness to vaccine boost

We addressed the question of primed CD8 T cell responsiveness to boost in a Balb/c mouse model of vaccination against gag of HIV-1, namely intramuscular (i.m.) prime with the Chimpanzee adenovector ChAd3-gag and i.m. boost with Modified Virus Ankara MVA-gag. In this setting, boost was more effective at day(d)100 than at d30 post-prime, as evaluated by multi-lymphoid organ assessment of gag-specific CD8 T cell frequency, CD62L-phenotype and in vivo killing activity at d45 post-boost. RNA-sequencing was used to compare memory signature of gag-specific spleen CD8 T cells at d100 post-prime with those at d30. Bulk RNA was sequenced from sorted spleen gag-specific CD8 T cells (average 93% pure Tetr-gag+Pent-gag+CD3+CD8+ cells) at d30 and d100 post-prime, in 4 independent experiments with a total of 7 samples (A_d30; B_d30; C_d30; D_d30; B_d100; C_d100.1; C_d100.2).